1. Field of the Invention
This invention relates generally to devices which aid humans in walking. In particular, the invention relates to a device which is designed to be strapped onto a person and which provides assistance in lifting the proximal leg (that is, the thigh) while taking a step. The invention also relates to a device to be worn by a person in order to stabilize lateral support muscles to assist in overcoming pelvic sway (called "hip drop") during walking.
2. Description of the Prior Art
Many neurological conditions cause muscle weakness of the proximal leg and pelvic instability. The proximal leg flexor muscles are situated between the knee and the pelvic bones and are attached to the knee and pelvic bones. Such proximal leg muscle weakness may exist even though the lower leg muscles below the knee are not weak. The condition of pelvic instability is recognized by an apparent unsteadiness of gait which is due to pelvic sway and lack of lateral support muscles. The neurological conditions which cause proximal leg muscle weakness and pelvic instability include brain lesions on the side opposite the weak leg and lesions in the spinal cord. Furthermore, lesions in the nerve roots, lumbar plexus and femoral nerve can result in proximal leg weakness and as a consequence, gait disorders.
The neurological conditions described above are often placed into one of the following disease categories:
(1) Multiple Sclerosis (MS) with spastic leg muscle weakness; PA1 pelvic instability and gait unsteadiness; PA1 (2) Stroke with spastic hemiparesis; PA1 (3) Degenerative, traumatic and other spinal cord lesions; and PA1 (4) Inflammatory, auto-immune and compressive lesions of the lumbar roots, lumbo-sacral plexus and femoral nerves.
The prior art has provided many braces designed for conditions known as foot drop and knee weakness, but devices have not been designed to aid a patient having proximal leg muscle weakness which is the primary factor resulting in gait instability. Examples of prior art leg braces follow.
U.S. Pat. No. 2,111,018 to Ahlar discloses a walking brace which includes a belt worn around a users waist and upper and lower leg braces which are strapped about a users leg.
U.S. Pat. No. 1,072,369 to Spahn discloses a knee and ankle brace with an upper portion fitted about the upper leg, a lower leg portion and a spring/lever arrangement connected between the upper and lower portions.
U.S. Pat. No. 5,054,476 to Petrofsky et al. discloses an orthosis for walking assistance, especially for people who have been paralyzed by a spinal cord injury. Upper leg braces are provided as a pair, one for each leg. Risers extend upwardly from the leg braces to a pelvic band. The risers are flexible. Hip joints couple the risers to the leg braces.
U.S. Pat. No. 5,743,837 to Dias et al discloses a body mounted device for exercising buttocks muscles. The device includes two hinge plates which are secured outwardly and to one side of respective hip joints of a user, where each of the hinge plates are provided with a pivot arm which pivots about the hinge plate. The pivot arm extends downwardly along the legs of the user, engaging the backs of he legs between the hip joints and knees. A resilient elastic band provides a forwardly directed biasing force on the back of the legs. During rearward pivoting of the legs, the muscles of the buttocks contract and are forced to overcome the biasing force exerted by the pivot arms on the legs of the user.